how its possible..such high compression with winrar

[ashishstillthere]

hi guys i have one winrar file and it contain an iso file of window 6-1 xp 64 bit




now the main thing

size of winrar approx 10 mb
size of iso file approx 3.25 gb



plz tell me how this can be possible

its not of kgb file.just iso n such high compression.how to do this with winrar

 

[n2casey]

I think that is not an ISO file.
It is a simple text file, having lot of repeated text inside to make it large size file & is then saved with .iso extension and then compressed to RAR

 

[victor_rambo]

I think Raaabo has once told about it. He said it something pertaining to 'patterns'.

 

[dheeraj_kumar]

Its just an ISO with lots of dummy files filled with 0s in order to create patterns. Compression works this way -

suppose you have a string 54545454555443dfgretttgdftqtqtqltn43hngf43u4905u45 repeated thrice in the file, you store it in an index, and replace all instances of the string with the index number.

Now, look at how repeated zeroes in our case can reduce file size:

take a string 000000000000000000000000000000000000000 which is say 40 zeroes. it is found say 4 times in the file. but notice that this string is a pattern by itself - it has 40 0s. so the compressed form will look something like 40 00 and stored in the index, and each reference to the long string points to the index.

you just compressed 40 characters to 2 characters, and as its found in 4 places, its 160 chars to 8 chars = 95% compression.

 

[comp@ddict]

Well, afaik highest was KBG doing 1GB to 100MB

But what's the use, when u take a lifetime compressing and decompressing it

 

[ashishstillthere]

I think that is not an ISO file.
It is a simple text file, having lot of repeated text inside to make it large size file & is then saved with .iso extension and then compressed to RAR

no bro its an iso file an i have extracted its content by using alcohal





thanks dheeraj for the xplanation now plz tell me how to do that

here is the link for the file plz check it and tell me

~snipped~

 

[gopi_vbboy]

it depends on compression algorithm....7z is good but not stable

 

[Cool Joe]

Thanks a lot for that piece of info dheeraj_kumar.

@compaddict- There have been DVD sized files compressed to less than 2 MB using KGB archiver.

 

[ashu888ashu888]

BUt, 6 to 7GB of GAME ISOs hv been converted to 1.5GBs or so.. (esp the torrent version of games)
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Its simply this: compress sound files to .ogg format and compress game video files( .bik) into just half of them. Now compress all data with 7zip and rename it with .x extension......

(this is NOT my explaination).. but this is wat they (ppl like skullptura on torrents) do) maybe its not jus ONLY winrar...

 

[ashishstillthere]

thanks alot for your reply but what about the nrg/iso type file

 

[ashu888ashu888]

7zip has such a ability to compress files, but not tested myself though...found from google..

 

[Cool Joe]

Yeah. 7zip has a high compression ratio, higher than that of WinRAR. I've tested this myself.

 

[dheeraj_kumar]

@ashish
First, remove the link. India runs on warez, but its not allowed in digit forum, atleast not in public.
Second, Install it in a virtual machine, my guess is it wont install, or it will, with minimal features only. Try it and post back.

 

[ashu888ashu888]

Yeah. 7zip has a high compression ratio, higher than that of WinRAR. I've tested this myself.

cool, on wat hv u tried?? Musiz files, docs, movies or game ?? plz post..also wat compression u got, i mean the file size b4 7Zipping and the size of file after 7Zipping ??

@ashish
First, remove the link. India runs on warez,

true, very true,lol.. infact the whole world is ditching MS (especially) and running on pirated OS stuff..

 

[Cool Joe]

^^GTA SA original size:: 5.5 GB
Compressed size:: 3.3 GB

And you can get better compression with documents.

 

[ashu888ashu888]

^^ hey thats awesome... will try that for all my stuff too.. thanx beta for the update on this..

wat was the time taken for compression (not decom as it hardly takes any huge time)

btw, its free (7zip) isint it ?? like winrar???

 

[Cool Joe]

Yep, 7zip is free. On my system- AMD Athlon 64 1.81 Ghz, 1 GB DDR400 RAM, it took around 2 hrs. The computer was left idle at this time.

 

[comp@ddict]

Well, ya...so iso's can be compressed to a high level too.

I hav a CD of a game, wanna make an ISO copy of it. Is there any software, good, free, small?

 

[dheeraj_kumar]

^^ Depends, you might need to use Alcohol 120% depending on the protection.

 

[ashu888ashu888]

^^

also, adding to the point, how much RAM u hv and for how much time can u leave ur system idle (wen the compression is goin in progress)

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Also, as beta_testing said, tat it took him 2 hrs wen system was kept idle, well i wud probably stick to the original file size and use a DVD or 2 DVDs than waiting for such time..

but, yes the compression ratio was really good..
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@ dheeraj, nice, enlightening siggy..